1. Field of the Invention
This invention relates to distance and methods, and more particularly to systems and methods in which a signal transmitted to the target is compared with a signal reflected back from the target to determine the round trip distance, and thereby the distance to the target.
2. Description of the Prior Art
Numerous systems are available for accurately measuring long distances. For example, precise long distance measurements can be obtained by transmitting a radar signal to a target and observing the signal transit time, either one-way or round trip. Similarly, a variety of sensors are available for obtaining accurate measurements of short distances. However, it is difficult to accurately measure medium distances in the range of about 1-10 meters. Fast response, non-contact medium distance measurement systems are desirable for various applications, such as robotics control, manufacturing and testing.
One of the problems with non-contact measurement systems in the medium distance range is that it is difficult to accurately measure the signal transit time from a reference source of electromagnetic radiation to a target. Electromagnetic radiation can normally complete a round trip to a medium distance target within an elapsed time in the nanoseconds regime. It is very difficult to accurately measure such minute time spans.